1. Field of the Invention
The present invention concerns installations for bringing a liquid and a gas into contact, and concerns especially atmospheric coolers or cooling towers, provided with a packing means through which the liquid falls due to gravitational force and the gas flows in counter-current to the liquid. The installations for bringing a liquid and a gas into contact comprise a chamber or tower in which the packing means is installed. Such means may be constituted by an assembly of tricking panels or sheets, generally of a profiled type.
The invention relates to a sheet-type packing means for such installations, and also to the sheets of which such a means is constituted.
2. Description of the Prior Art
Such assemblies have been described especially in patents (U.S. Pat. No. 3,830,684) (GB No. 1,495,788), (U.S. Pat. No. 4,344,899) and (U.S. Pat. No. 4,581,183)).
The tricking sheets described for example in U.S. Pat. No. 4,344,899 and U.S. Pat. No. 4,581,183 comprise, in a direction parallel to the crests of the corrugations, that is to say vertically when the sheet is in service, an even number of successive zones of equal extent in this direction but which differ from one another in the amplitude of the corrugations. Along the crest line of the corrugations there may be seen at least one pair of zones constituted by a zone with corrugations of a first amplitude and a zone with corrugations of smaller amplitude or, in the extreme case, of zero amplitude, which zones are connected to one another by a transition zone. The packing elements are constituted by juxtaposition of identical trickling sheets positioned alternately in one direction and in the opposite direction defined by rotation of the sheet through 180.degree. about an appropriate axis which depends on the geometry of the sheet and in particular on the corrugations and points of contact provided in the two kinds of corrugation zones.
These trickling sheets are manufactured from strips of indeterminate length.
Since the zones of different corrugations separated from one another by a transition zone follow one another vertically when the sheets are in place in the packing element in service, the inversion of the corrugations from one zone to the other gives rise to a baffle effect particularly susceptible to soiling in the region of the transition zone.
The channels thus formed follow a tortuous course which does not make for easy maintenance.
Soiling may be due to substances in suspension, in the case of the cooling of dirty, contaminated, or simply inpure water. Moreover cooling towers through which aerated lukewarm water generally passes are particularly prone to the development of various microorganisms, especially bacteria and algae. Not only can these microorganisms, especially the algae, block the channels themselves, but they can also fix the fine substances in suspension in the water, such as particles of sand or silt.
The sheets are generally produced by unwinding strips in the sense of the length of the packing elements, transversely to the crest lines of the corrugations. In this case the width of the strip and the height of the sheets in service are limited by the width of the forming tool. It is then necessary to stack two or more packing elements to reach the required height for packing means in tower coolers. The relative positions of the packing elements are in this case not very precise because of their low rigidity, not only at the time of assembly but also when subjected to thermal expansion and the turbulence of the water and air. As a result, the channels of one packing element do not correspond to those of the adjacent lower and upper packing elements. This is another cause of forming bottlenecks to the flow of water and air, giving rise to the retaining of substances in suspension and to conditions propitious for the development of microorganisms.